Numerical Modelling and Analysis of the Left Ventricle
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The development of a well functioning finite element model of the left ventricle is an important step to better understand the pumping function of the human heart. This may be of interest when developing effective treatments for different heart diseases. The goal of this thesis is to develop a finite element model of the left ventricle, taking into account the material properties and complex structure of the myocardium. The model uses a truncated ellipsoid as geometry and is assigned a linear, transmural variation of both fiber and sheet orientations in the myocardium. Using existing constitutive models of the myocardium, the deformation of the ventricle in systole was analysed using a simple, active stress component. The behaviour of the model was evaluated using the parameters: ejection fraction, torsion, wall thickening, longitudinal shortening and radial shortening. Describing the left ventricular function, these parameters are compared with the physical values. The results show that in order to realistically model the different ventricular features, active stress components in fiber, sheet normal and shear (sn) directions are all needed. The model is not able to show a realistic ejection fraction even when the active stress contribution is raised to non-physiological levels. The model has in particular problems of producing wall thickening and radial displacement, but still a relatively realistic systolic contraction is seen. The model significantly overestimates the left ventricular torsion. This is in part due to the symmetrical geometry and the fact that the right ventricle is not included.